The present invention relates to cemented carbide components which are cast into low carbon steel. The components are especially suitable for roller cone bits, impact rock crusher arm/impellers, point attack tools, dredging teeth and sliding wear parts.
U.S. Pat. No. 4,119,459 discloses a composite body with cemented carbide and a matrix of graphitic cast iron-base alloy with a carbon content of 2.5-6%. U.S. Pat. No. 4,584,020 and U.S. Pat. No. 5,066,546 claim that the steel matrix should have a carbon content between 1.5 and 2.5%. U.S. Pat. No. 4,608,318 discloses a powder metallurgical method to obtain composite material bodies during solid state sintering and bonding the metal compact to said compact. U.S. Pat. No. 6,171,713 describes a composite of white iron alloys and cemented carbide-granules. The melting point is 1480-1525° C. WO 03/049889 describes consolidated hard materials, method of manufacture and applications. The consolidation takes place below the liquidus temperature of the binder metal using rapid omnidirectional compaction (ROC) or hot isostatic pressing (HIP).
The ductile cast iron used in the prior art has generally a low hardness of about 38 HRC and low alloy steel casting has a hardness of between 40 and 53 HRC. Thus the matrix of a low alloy steel will have about twice the strength of a comparable cast iron product according to prior art.
From the above cited prior art it is evident that cemented carbide is preferably cast into an iron alloy with relatively high carbon content to form a body which body is subsequently cast into an iron alloy with lower carbon content, e.g., U.S. Pat. No. 4,584,020 and U.S. Pat. No. 5,066,546.